Summary
Oxia affected by server crash via race condition in session heartbeat handling
A race condition between session heartbeat processing and session closure can cause the server to panic with send on closed channel. The heartbeat() method uses a blocking channel send while holding a mutex, and under specific timing with concurrent close() calls, this can lead to either a deadlock (channel buffer full) or a panic (send on closed channel after TOCTOU gap in KeepAlive).
Details
In oxiad/dataserver/controller/lead/session.go, the heartbeat() method performs a blocking s.heartbeatCh <- true send. If the channel buffer is full (size 1), this blocks while holding the session mutex, preventing close() from acquiring the lock to close the channel, a deadlock.
Additionally, in session_manager.go, KeepAlive() releases the session manager's read lock before calling heartbeat(), creating a TOCTOU window where the session can be removed and closed between the lookup and the heartbeat call.
Workarounds
No workaround available.
Impact
A remote client can trigger a server crash by sending rapid KeepAlive requests while a session is expiring or being closed. This is a denial-of-service vulnerability that crashes the entire data server process.
All versions are affected.
Multiple concurrent operations access a shared resource without proper synchronization, producing unpredictable results depending on timing. Typical impact: TOCTOU exploits, data corruption, or privilege escalation.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Fixed by changing heartbeat() to use a non-blocking select with a default case, and by holding the session manager read lock through the entire KeepAlive() operation.
Frequently Asked Questions
- What is CVE-2026-40943? CVE-2026-40943 is a high-severity race condition vulnerability in github.com/oxia-db/oxia (go), affecting versions <= 0.16.1. It is fixed in 0.16.2. Multiple concurrent operations access a shared resource without proper synchronization, producing unpredictable results depending on timing.
- Which versions of github.com/oxia-db/oxia are affected by CVE-2026-40943? github.com/oxia-db/oxia (go) versions <= 0.16.1 is affected.
- Is there a fix for CVE-2026-40943? Yes. CVE-2026-40943 is fixed in 0.16.2. Upgrade to this version or later.
- Is CVE-2026-40943 exploitable, and should I be worried? Whether CVE-2026-40943 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-40943 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-40943? Upgrade
github.com/oxia-db/oxiato 0.16.2 or later.